1. Field of the Invention
The present invention relates to a projector, and in particular, to a fixed shift type projector in which an image forming panel is shifted and fixed.
2. Description of the Related Art
A projector which projects light with an image by a light modulation device (a device which forms an image, and is referred to as an “image forming panel”), such as a liquid crystal display (LCD) or a digital micromirror device (DMD), toward a projection surface (for example, a screen) and displays the image on the screen is known.
In the projector, light (illumination light) emitted from a light source device is given an image according to an image signal (image information) by the image forming panel and is emitted from the projection lens as image light, and the image is projected onto the screen on an enlarged scale. If an optical axis of the projection lens is perpendicular to the screen, the image displayed on the image forming panel is enlarged as it is and projected onto the screen; however, usually, there are many cases where the screen is disposed upward the projector.
In this way, in a case where the screen is disposed with being shifted with respect to the optical axis of the projection lens of the projector, the image forming panel is disposed with being shifted in a direction opposite to a direction in which the screen is shifted with respect to the optical axis of the projection lens, whereby it is possible to project the image displayed on the image forming panel onto the screen as it is on an enlarged scale (fixed shift type projector).
As the projector of the related art, for example, JP2011-209394A describes that heating control of a group of a plurality of lenses provided in a traveling direction of light is performed, thereby eliminating variation of a focal position of a projection optical device with an increase in temperature of a projection lens. JP2010-243542A describes that the inside of a lens barrel including a lens is cooled, thereby cooling an aberration correction lens, suppressing change in aberration of a projection lens due to an increase in temperature, and preventing deterioration of quality of a projected image.